1. Field of the Invention
The present invention relates to a spline lubrication apparatus for lubricating a spline. More particularly, the present invention relates to a spline lubrication apparatus for lubricating a spline of a pump drive.
2. Background Information
Spline wear is a very big factor when working with any large engine. The reason behind this is because internal combustion engines are ignited by compression. When the engine fires, there is a very strong pulse of engine rotation torque, as a piston approaches Bottom Dead Center (BDC). The inertia of the rotating parts must drive the piston back up and create a compression for the next cycle. As the inertia from the rotating parts start driving the engine, an anti-engine torque is applied. For a split second between engine and anti-engine torque, all components are in a neutral, no power state. During this time all bushings are free to, and do, move. With a dry spline the combination of this movement and torque in both directions causes excessive, premature wear. Such wear is prevented by introducing oil to the spline area. Many manufacturers use several different methods of oiling the spline. Most, if not all of these include a remote oil supply and/or a pump to get oil to a sufficient level in the spline area.
According to the present invention which includes a modular split-housing design, the wet spline feature is cast into the housing. As the gears spin, oil is distributed throughout the box. The cast ports are strategically placed to catch the maximum amount of oil and direct it to the rotating spline. Shielded bearings are used to restrict oil flow back into the sump of the gear box. This causes the oil to back up and fill the spline cavity. With oil being retained in the cavity this causes the bearings to be partially submerged, giving better lubrication benefits. The bearings also run cooler because of the oil being passed through the bearing, instead of being submerged into the main sump. An added benefit of retaining oil is during cold start conditions. In other manufacturers' designs, the bearings are oiled by splash. With cold thick oil, there is insufficient lubrication until the oil warms up. When oil is contained in the spline cavity, the bearings have lubrication upon start up, no matter what temperature or thickness of oil used. With the oil ports being cast into the housing, under normal operation, they will act as oil fill and oil level holes. This is opposed to other designs where oil ports are cast into the adapter groups. Traditionally these have four cast holes approximately 90 degrees apart. That design allows oil to flow in but would also drain out just as quickly, thus again, relying on a splash lubrication for both the bearing and the spline. Adapter groups with two ports cast therein would allow for proper oil flow and oil level. However, the attachment orientation of these adapters would be critical for proper oil retention. Having the two ports cast into the housing eliminates the need for the critical orientation of these adapter groups. A third design is to cast only two ports to allow for fill and level. This provides similar characteristics to the modular split housing design of the present invention. However, open ball bearings or taper roller bearings are used. Both of these bearings provide little to no oil retention, and actually the taper roller bearings tend to pump the oil out.
In the modular design according to the present invention, there is ease of assembly and serviceability. The modular design is built from two housing halves containing both the gears and bearings. This is different from current designs in that currently the adapters (pump pads or engine adapters) contain the bearings. This is used because in a mono-body (uni-body) housing, the gears must either be installed through the pump pad holes, or through the engine adapter hole and slid over to the proper location. The shafts are then pressed onto the gears. Finally, the covers, containing the bearings are installed. This is a very time consuming process and causes lots of difficulty in the field for repairs. Most of the time, the gear boxes must be completely disassembled from the machine and either sent to a repair site that has the proper equipment, or sent back to the manufacturer of the gear box. A modular split-housing design eliminates all of these problems. A modular split housing according to the present invention uses solid on shaft (SOS) gears in which both bearings are pressed onto the shaft. In the event the customer would require less oil in the spline area, a nonshielded bearing could be used. The housing halves contain the bearings so that when the gearbox is bolted together, all internal rotating parts are contained therein. Repairs are also simplified with a modular split housing. If anyone of the gears or bearings were to fail, the modular split housing would be able to stay attached to the engine or motor, while the second half including the pumps, would be removed. Because the pump pads do not contain the bearings, the pump would not have to be removed when disassembling. Once taken apart, the gears/bearings will slide out by hand and can be fixed or easily replaced. Again, because the modular split housing is fully contained, the end user can purchase individual adapter groups to replace or modify the original configuration. All adapters (input and output) can be added without having to disturb the box or any internal workings.
The modular-split housing uses the same gears and bearings throughout several models, because the configuration of the housings is the same. This is beneficial in two ways. For the manufacturer, fewer gears need to be produced. For the consumer, parts availability is improved, whether for service or for new pump drive orders. This will save much misunderstanding on the part of both the consumer and the manufacturer, which will speed up the process of sending repair parts. All the gears throughout the product line use the same large internal spline. With a large internal spline and with oil lubrication, fretting corrosion is theoretically eliminated. The larger splines create a common geometry in the gears, resulting in fewer parts. The benefit to the end user includes, the variety of pump spline adapters available which offers flexibility when changing pumps and the larger gear spline bore has increased rating which if and when spline wear occurs, due to excessive HP draw, the smaller pump spline will wear before the gear spline. When this happens, the bushing can be easily replaced without replacing the gear.
When producing a mono-body housing, many times residue is left in corners and covered by paint. This has been reported to come loose during operation causing bearing and/or gear failure. Because mono-body housings are so large one casting must cover all sides. This causes a potential for air pockets, and voids while pouring the casting. When a casting has voids, it reduces the integrity tremendously and also offers a place for oil to leak. With a modular split-housing according to the present invention and the resultant two housing halves, a consistent pour is more repeatable, and cleaning and inspection is much easier.
Some of the features and benefits derived from the subject invention are as follows:    1. The modular design means that the base unit can be built without the need for input and/output adapter groups. Also, the bearings and gears are self-contained within the housings. Furthermore, input and output adapters can be added at anytime prior to the installation of the unit.    2. The solid-on-shaft gears provide consistent and uniform alignment. Also, such gears simplify assembly once the bearings are pressed on the gear shaft. Additionally, such gears reduce the total number of parts.    3. The arrangement simplifies service and does not require pressing the shafts through the housings into bearings and gears. Also, the present arrangement does not require shimming or special adjustment of the pump pads and input adapters.    4. There are fewer parts and the adapter groups are reduced to a single set of input housings and output pads for the entire product line. The total of 31 gears are interchangeable across different models.    5. The wet spline includes oil passages that are built into the housings along with the bearing design to create a constant oil bath for the bearings and splines, resulting in longer, trouble-free operation.    6. The drop-in replacement arrangement enables interchangeability with present pump drive lines and with other types of pump drive lines.    7. The higher rating means an increased horsepower rating over the present product line and competition.    8. The arrangement according to the present invention provides an apparatus which also runs quieter, is less costly and which reduces lead time.
Therefore, it is a primary feature of the present invention to provide a spline lubrication apparatus for lubricating a spline of a pump drive that overcomes the problems associated with fretting corrosion or excessive wear.
Another feature of the present invention is the provision of a spline lubrication apparatus for lubricating a spline of a pump drive gearbox that is easy to disassemble.
A further feature of the present invention is the provision of a spline lubrication apparatus for lubricating a spline of a pump drive gearbox that reduces the cost of manufacture.
Other features and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description of a preferred embodiment of the present invention contained herein.